A structural filler is installed in a gap between at least first and second composite members by extruding a flowable filler material, placing the extruded filler on one of the composite structural members, and assembling the composite members.
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1. A method comprising:
extruding an uncured flowable filler material directly onto a substantially flat composite charge, wherein extruding is performed by a dispenser supplied with said uncured flowable filler material, and wherein the uncured flowable filler material comprises a stiffness sufficient to maintain a predetermined cross-section after extruding and prior to shaping or curing;
forming the substantially flat composite charge into a first composite member; and
assembling the first composite member and a second composite member following said extruding.
4. A method comprising:
forming a length of an uncured filler having a predetermined cross-sectional shape by extruding a flowable filler material directly onto a substantially flat substrate, wherein the uncured filler comprises a stiffness sufficient to maintain the predetermined cross-sectional shape following extruding and prior to shaping or curing, and wherein said extruding is performed by a dispenser supplied with said flowable filler material;
controlling, while forming, a rate at which the flowable filler material is extruded;
controlling, while forming, a viscosity of the flowable filler material;
forming the substantially flat substrate into a first composite member;
installing the first composite member on a second composite member; and
co-curing the length of the uncured filler, the first composite member, and the second composite member.
2. The method of
controlling a viscosity of the uncured flowable filler material immediately prior to extruding; and
controlling a volumetric rate of extrusion of the uncured flowable filler material.
3. The method of
5. The method of
forming the length of the uncured filler is performed by relatively moving said dispenser and said substantially flat substrate, and
extruding the flowable filler material includes extruding the flowable filler material through a nozzle onto the substantially flat substrate.
6. The method of
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This disclosure generally relates to methods and equipment for producing composite structures, and deals more particularly with the extrusion of structural adhesives used as fillers between composite parts.
When composite structural members are joined together, gaps or voids may be present along bond lines between the members which may need to be filled in order to increase the strength of the bond. For example, in the aircraft industry, composite fuselage stiffeners such as stringers may include adhesive filler at the radius bond line between the stringer and a fuselage skin. Voids may also be present where plies are bent or folded during layup. The adhesive filler is applied in the form of triangular cross section strips, sometimes referred to as noodles or fillers, which fill the voids at the bond line. The fillers may be fabricated from laminated strips of adhesive that are precision cut and roll formed in a sequential manner. This fabrication process requires inspection for foreign object debris, as well as hand installation of the filler into the stringer. Thus, the current process is labor intensive, may require close quality control and necessitates the prefabrication of the fillers prior to installation. Because the fillers must be prefabricated, they may be required to be stored in a chilled environment, typically in a freezer, so that their shape is maintained. Moreover, because of the precision cuts and sequential forming process, the current process may be difficult to automate.
Accordingly, there is a need for a method of forming adhesive fillers that may reduce labor costs, processing time and the need to prefabricate the fillers in advance of their installation.
According to the disclosed embodiments, a method and apparatus are provided for fabricating fillers that reduce processing time and labor costs by extruding the fillers. The fillers may be extruded either directly onto a composite structural member in order to fill a void in a composite structure, or onto a tool that may be used to maintain the cross-sectional shape of the filler and place the shaped filler on a structural member. The disclosed method may substantially eliminate the need for prefabricating and storing fillers.
According to one disclosed embodiment, a method is provided for installing a structural filler in a gap between at least first and second composite members. A filler is formed by extruding a flowable filler material and placing the filler on the first composite structural member. The first and second structural members can then be assembled with the filler positioned within a gap between the composite members. The filler may be placed on the first composite member by extruding a flowable filler material directly onto the first composite structural member, or by extruding the filler onto a tool which is then used to place the filler on the structural member. The method may also include controlling the viscosity of the filler material as it is dispensed by heating the filler material to change its viscosity.
According to another method embodiment, a structural filler for composite structures is formed by forming a length of an uncured filler by extruding a flowable filler material. The rate at which the flowable filler material is extruded may be controlled. The viscosity of the flowable filler material may also be controlled. The extruded length of the filler material is cured and then formed by relatively moving a dispensing gun and a substrate, and extruding the flowable filler material through a nozzle onto the substrate. In one embodiment, the substrate may comprise a structural member, while in another embodiment, the substrate may comprise a tool used to place the filler onto a structural member.
According to another embodiment, apparatus is provided for producing a structural filler for a gap in a composite structure. The apparatus includes means for extruding a filler onto a tool. The tool may be used for transferring the filler onto a composite structure. The dispensing means may include a body adapted to hold flowable filler material and a nozzle through which the flowable filler material may be extruded. The dispensing means may also include means for forcing the flowable filler material to flow from the body through the nozzle. Means may be provided for controlling the viscosity of the flowable filler material.
The disclosed embodiments satisfy the need for a method and apparatus for extruding adhesive fillers which reduces processing time, labor costs and may obviate the need for prefabrication and storage of fillers.
Referring first to
Referring particularly to
Additional details of the apparatus 25 are illustrated in
The body 40 may be formed of a thermally conductive material such as, without limitation, metal and may be surrounded by an electrically powered heating blanket 44 which may be used to heat the adhesive material 45 and thereby control the viscosity of the adhesive material 45, and thus its flow characteristics. The temperature of the heating blanket 44 may be controlled by a controller 52. While a heating blanket 44 has been illustrated in the disclosed embodiments, a variety of other techniques and devices may be employed to heat the adhesive material 45. A motor 46 operated by controller 52 is connected through a screwdrive 66 to the plunger 64. Operation of the motor 46 controls displacement of the plunger 64 which applies pressure to the adhesive material 45 within the cartridge 42, forcing the latter to be extruded through the nozzle 50 at a rate determined by the speed of the motor 46 and the controller 52.
The rate at which the adhesive material 45 is extruded through the nozzle 50 may be determined by stored programs 70 used to operate the controller 52. For example, an operator may input a part number at 72 which results in the selection of a particular stored program 70 that determines the rate of extrusion for a particular part.
Additional details of the nozzle 50 are illustrated in
Attention is now directed to
In the embodiment illustrated in
Attention is now directed to
In use, adhesive filler 32 is extruded directly onto the tool 88 using the dispensing gun 30 previously described (see
The beveled surfaces 95 assist in maintaining the triangular shape of the extruded adhesive filler 32 until the filler 32 is ready to be placed on the stringer 36. However, to further aid in maintaining the shape of the adhesive filler 32, the tool 88 may be chilled.
Attention is now directed to
With the adhesive fillers 32 lightly adhered to the carrier plate 96, the carrier plate 96 is transported to the location of the stringer 36 which in this example is shown as being supported in the tools 92, 94. The carrier plate 32 is then inverted, and vertically aligned above the area 90 where the fillers 32 are to be placed. The carrier plate 96 is then moved downwardly until the fillers 32 contact and adhere to the stringer 36, following which the carrier plate 96 may be returned to the block 98 in preparation for the next installation sequence.
Referring now to
A further method embodiment is shown in
Referring next to
Each of the processes of method 150 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.
As shown in
The apparatus embodied herein may be employed during any one or more of the stages of the production and service method 150. For example, components or subassemblies corresponding to production process 158 may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft 152 is in service. Also, one or more apparatus embodiments may be utilized during the production stages 158 and 160, for example, by substantially expediting assembly of or reducing the cost of an aircraft 152. Similarly, one or more apparatus embodiments may be utilized while the aircraft 152 is in service, for example and without limitation, to maintenance and service 166.
Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.
Anderson, Michael R., Jones, Darrell D., Brennan, Joseph D., Sherwood, Travis J., Robins, Brian G.
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Dec 02 2008 | SHERWOOD, TRAVIS J | Boeing Company, the | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 021950 | /0724 | |
Dec 02 2008 | ROBINS, BRIAN G | Boeing Company, the | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 021950 | /0724 | |
Dec 02 2008 | ANDERSON, MICHAEL R | Boeing Company, the | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 021950 | /0724 | |
Dec 05 2008 | JONES, DARRELL D | Boeing Company, the | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 021950 | /0724 | |
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Dec 09 2008 | BRENNAN, JOSEPH D | Boeing Company, the | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 021950 | /0724 |
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